1. Field of the Invention
This invention relates to a device for dispensing a dose of a medicant, and more particularly, a medicant dispensing device which is activated by the user upon inhalation of air from the interior of the housing of the device.
2. Description of the Prior Art
U.S. Pat. Nos. 3,456,644; 3,456,646; 3,565,070; 3,636,949; 3,732,864; 3,789,843; 3,814,297; 3,826,413; 4,648,393; 4,664,107; and 4,648,393 all disclose a breath-activated inhalation device wherein a dose of a medicant is dispensed from an aerosol container to be mixed with air drawn into the housing of the inhalation device upon inhalation by a user. Each of these patents illustrate a device wherein the air drawn from the exterior of the housing upon inhalation by the user opens a valve and flows through an opening normally closed by the valve into the interior of the housing. Movement of the valve in turn causes movement of a linkage arrangement to permit the aerosol container to drop or be moved downwardly to open the aerosol valve of the container so that a measured dose of a medicant can be inhaled with the air entering the housing.
Perhaps the most analogous disclosure to that of the present invention is illustrated in U.S. Pat. No. 3,456,644. Upon inhalation, a valve 66 floats up sleeve 63 allowing air to enter a housing 22 through openings 65 and 62. The valve 66 strikes lever 51 causing it to rotate in a clockwise direction as viewed in FIGS. 2 and 3 of the drawings. The pivoting of the lever releases a pawl 53 from contact with a groove 54 on a block above the medicant-carrying container in the housing of the device, enabling a pair of springs 49,50 to extend, to push the block against the bottom of the container, causing it to move downwardly to open its aerosol valve, so that medicant can be dispensed into an air passage in the housing for inhalation with the air drawn into the housing from the exterior of the housing. The lever 51 is reset by pushing the medicant-carrying container back to a position wherein the pawl can reseat in the notch 54 to hold the container in a raised position. This is accomplished by exerting pressure on stem 43 to move the container upwardly relative to its aerosol valve to close the container.
While the inhalation-actuated aerosol dispensing device of U.S. Pat. No. 3,456,644 is structurally similar and does disclose the concepts involved in the present invention, the toggle linkage arrangement used in the present invention for holding the aerosol valve in its closed position by precluding the drop of medicant-containing bottle relative to the valve under the urging of the coil spring is different. In lieu of the pawl and notch arrangement, the present invention utilizes a toggle linkage so that when the arms of the linkage are aligned in a linear fashion, the force of the coil spring cannot urge the container to drop to open the aerosol valve. This lock linkage ensures activation of the device only upon inhalation by a user.